public static MvcExternalResources GetInstance(UrlHelper helper)
        {
            const string instanceKey = "ExternalResourcesInstance";

            var context = HttpContext.Current;
            if (context == null)
            {
                return null;
            }

            var instance = (MvcExternalResources)context.Items[instanceKey];

            if (instance == null)
            {
                context.Items.Add(instanceKey, instance = new MvcExternalResources(helper));
            }
            return instance;
        }
        public static MvcExternalResources GetInstance(UrlHelper helper)
        {
            const string instanceKey = "ExternalResourcesInstance";

            var context = HttpContext.Current;

            if (context == null)
            {
                return(null);
            }

            var instance = (MvcExternalResources)context.Items[instanceKey];

            if (instance == null)
            {
                context.Items.Add(instanceKey, instance = new MvcExternalResources(helper));
            }
            return(instance);
        }